It was found (Robinson, Palmer, and Burrows 1951) that salmon roe 

 plus 10 percent viscera meal added as a binder, fed as total, diet to 

 young blueback salmon for a 24-week period induced greater growth than 

 any ccsnbination of meat glands, viscera, and meal that had yet been 

 tried. This increased growth was significant in contrast to the much 

 poorer rate of growth obtained with the other fractions of salmon viscera. 

 The lower growth rate of the fish fed viscera fractions other than roe 

 was accompanied by an increased rate of mortality. This indicates that 

 salmon roe contained the greatest growth potential for blueback salmon 

 fingerlings of any food material yet tested. However, it was noted 

 that during the first 12 weeks of the 24-week feeding period, the mort- 

 ality rate of the fingerlings fed the salmon roe was somewhat hi^er 

 than that observed for fingerlings fed the beef liver or mixed-meat- 

 glaud diets. This fact was considered in planning the 1950 feeding 

 trials. 



Fingerlings fed tuna livers with 10 percent viscera meal added as 

 a binding agent, did not develop anemia; however, the diet did not sup- 

 port normal growth. The 1950 experimental program included a test to 

 determine whether or not yellowfin tuna livers could replace beef liver 

 in a mixed meat-gland-viscera-meal diet. 



The 1950 program 



The experimental program for 1950 was designed to evaluate some 

 new feeding materials not previously tested as well as to corroborate 

 earlier findings. Vlhole true cod was fed as 30 percent of a mixed diet. 

 Halibut "sawdust", the band-saw residue resulting from preparation of 

 steaks from frozen halibut, was included in a mixed diet as a source of 

 protein. Continued experiments on the addition of fish meals to the 

 diets included mackerel offal meal, a meal not previously tested. Pre- 

 liminary trials on the effect of addition of two types of animal protein 

 factor (APF) supplements to mixed diets were carried out. Also, experi- 

 ments were carried out to determine the detrimental effect, if any, on 

 salmon fingerlings of diets of salmon roe containing added preservatives* 



The 1950 experimental program was modified from previous years in 

 that two feeding periods of diet evaluation were set up. The first period 

 of 12 weeks duration was arbitrarily designated as the cold water period 

 because the average water temperatures in which the fish were maintained 

 were below 50° F. The second period was designated as the warm water 

 period because the average tanperatures were above 50° F. It had been 

 observed during previous feeding trials that if a diet proved to be 

 inadequate during the warm water feeding period, it was definitely not 

 suitable for cold water feeding. Dried meals which normally produced a 

 lower gjrowth rate than the wet products, were fed only after the water 

 temperature had reached 50° F. By this feeding practice, it was hoped 

 that the greater growth rate obtained during the warm water period would 

 emphasize any measurable differences that might occur in the evaluation 

 of the new feeding materials. 



10 



